Calculating masses

Question 1

If 7g of magnesium reacts with x grams of oxygen and forms 18g of magnesium oxide, what is the mass of oxygen

Answer 1

18 - 7 = 11g

Question 2

If 0.145 moles of hydrogen react with 0.145 of chlorine and form 0.29 moles of hydrochloric acid, what is the equation

Answer 2

H2 + Cl2 —> 2HCl

Simplest ratio

Question 3

What is the limiting reactant

Answer 3

The reactant not in excess (is used up before the other reactant in the reaction)

Question 4

How can the law of conservation of mass be used to check answers

Answer 4

Mass of reactants = Mass of products

Question 5

Give a balanced symbol equation for:

Magnesium (7g) + Oxygen (11g) —> Magnesium oxide (18g)

Answer 5

0.29M + 0.34O —> 0.45MgO

Question 6

Give a balanced symbol equation for:

Magnesium (7g) + Oxygen (11g) —> Magnesium oxide (18g)

Answer 6

7/24 = 0.29
11/32 = 0.34
18/40 = 0.45

Question 7

What is the limiting reactant in a reaction of magnesium ribbon(4.8g) and hydrochloric acid(7.3g)

Balanced equation:
Mg + 2HCl —> MgCl2 + H2

Answer 7

.Steps.

1) 4.8/24 = 0.2 moles of magnesium
7. 3/36.5 = 0.2 moles of hydrochloric acid

2) Balanced equation shows we need 0.4 moles of hydrochloric acid. We don’t so HCl is the limiting reactant and magnesium is in excess

Question 8

What is the amount of product formed in a reaction determined by

Answer 8

The limiting reactant

Question 9

Why is there an equal number of atoms in Carbon and Carbon dioxide (C and CO2)

Answer 9

They have equal moles

Question 10

What factor of the product is determined by the limiting reactant

Answer 10

The mass of the product - no more product can be made when limiting reactant used up

Question 11

When is a solution formed

Answer 11

When a solute dissolves in a solvent

Question 12

What is the equation for calculating concentration in grams per decimetres cubed

Answer 12

Mass of solute(g)/volume(dm^3)

Question 13

What is the solute in an equation

Answer 13

The minor component in the solution